/*
 * Copyright (c) 2004, Swedish Institute of Computer Science.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the Institute nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * This file is part of the uIP TCP/IP stack
 *
 * Author: Adam Dunkels <adam@sics.se>
 *
 * $Id: memb.c,v 1.1 2006/06/12 08:21:43 adam Exp $
 */

/**
 * \addtogroup memb
 * @{
 */

/**
* \file
* Memory block allocation routines.
* \author Adam Dunkels <adam@sics.se>
*/
#include <string.h>

#include <types.h>
#include "memb.h"

/*---------------------------------------------------------------------------*/
void
memb_init(struct memb_blocks *m)
{
    memset(m->count, 0, m->num);
    memset(m->mem, 0, m->size * m->num);
}
/*---------------------------------------------------------------------------*/
void *
memb_alloc(struct memb_blocks *m)
{
    int i;

    for (i = 0; i < m->num; ++i) {
        if (m->count[i] == 0) {
            /* If this block was unused, we increase the reference count to
            indicate that it now is used and return a pointer to the
            memory block. */
            ++(m->count[i]);
            return (void *)((char *)m->mem + (i * m->size));
        }
    }

    /* No free block was found, so we return NULL to indicate failure to
       allocate block. */
    return NULL;
}
/*---------------------------------------------------------------------------*/
char
memb_free(struct memb_blocks *m, void *ptr)
{
    int i;
    char *ptr2;

    /* Walk through the list of blocks and try to find the block to
       which the pointer "ptr" points to. */
    ptr2 = (char *)m->mem;
    for (i = 0; i < m->num; ++i) {

        if (ptr2 == (char *)ptr) {
            /* We've found to block to which "ptr" points so we decrease the
            reference count and return the new value of it. */
            if (m->count[i] > 0) {
                /* Make sure that we don't deallocate free memory. */
                --(m->count[i]);
            }
            return m->count[i];
        }
        ptr2 += m->size;
    }
    return -1;
}
/*---------------------------------------------------------------------------*/

/** @} */
